In the electronic interconnection field, it is well-known that signal transmission through electrical cable may be adversely affected by electromagnetic and radio frequency interferences (EMI and RFI). Electrical cable, especially that formed in a flat array, known as ribbon cable, typically includes a metallic shield over the length thereof which provides a conductive path to drain such external interferences, thus reducing its adverse impact on signal transmission. While effectively providing a shield from EMI and RFI along the cable length, upon termination of the cable with an appropriate electrical connector, the shield is striped back at one end to expose the conductors for termination. Thus at the interconnections, the cable may not be adequately shielded.
Techniques are known which provide shielding of the cable and the connector at the points of interconnection. These techniques include surrounding the electrical connector with a metal housing, commonly referred to as a back-shell, and connecting the housing to the shield of the cable. Thus, the back shell will be at the same electrical potential as the cable shield. Since the back shell surrounds the connector, the point of interconnection will be shielded by the back shell. Often, the front face of the connector itself is housed in a metal shell which is used as ground for the contacts which extend therethrough. Thus it becomes desirous to connect the metal shell of the connector to the metal back shell to assure complete shielding.
In order to assure complete continuity between the shield of the cable and the shell of the connector, each contact point must be reliably maintained. Shielded connectors known presently in the art, provide a metallic spring clip which is inserted between the cable shield and the back shell. The spring clip maintains electrical contact between the shield and the back shell. A second similar spring clip is also used between the back shell and the shell of the connector.
As can be seen, this type of interconnection requires additional multiple ground connection interfaces, parts not normally required for transmission of electrical signals. Further, the parts should be designed to close tolerances to assure proper functioning. The back shell, being part of the conductive shielding part, would be constructed of highly conductive metal. It is apparent that shielding consideration significantly increases the cost of cable interconnection. The use of less costly materials, such as plastic or low-conductivity metal for back shells can not be implemented without compromising on shielding capabilities.